Table 2.

Examples of mild clinical phenotypes in carriers of disease-causing variants.

Gene	MIM *	Disease	MIM #	Inheritance	Biomarker	Clinical features	PMIDs
ABCD1	300371	Adrenoleukodystrophy	300100	XLR	Abnormal pattern of VLCFA	-	26718981
CTP2	600650	Carnitine palmitoyltransferase II deficiency, myopathic, stress-induced	255110	AR	Residual CPT activity	Myalgia, muscle weakness, rhabdomyolysis	15622536, 23184072
DMD	300377	Muscular dystrophy, Duchenne type	310200	XLR	HyperCKemia	Mild muscle weakness, calf hypertrophy	26718981
EMD	300384	Emery-Dreifuss muscular dystrophy 1, X-linked	310300	XLR	-	Heart involvement, cardiac symptoms later in life	25454731, 31718017
GJB1	304040	Charcot-Marie-Tooth disease, X-linked dominant, 1	302800	XLD	Abnormal nerve conduction velocities	Mild neuropathy, absent tendon reflexes	21254193
PLP1	300401	Pelizaeus-Merzbacher disease	312080	XLR	-	White matter abnormalities at MRI, mild neurological signs (spasticity, ataxia, cognitive impairment)	31137068, 23771846
RYR1	180901	Congenital myopathy 1B, autosomal recessive	255320	AR	HyperCKemia	Exertional myalgia, unexplained rhabdomyolysis, mild weakness	35428369
SGCA	600119	Muscular dystrophy, limb-girdle, autosomal recessive 3	608099	AR	HyperCKemia	Mild muscle weakness, exercise intolerance	14595658

AD autosomal dominant, AR autosomal recessive, CPT Carnitine palmitoyltransferase, VLCFA very long chain fatty acid, XLD X-linked dominant, XLR X-linked recessive.